Natural rubber, as a product, has been around for centuries. Historically, it had numerous applications, including manufacturing process improvement, aerospace, and automotive.
Unfortunately, natural rubber begins to degrade at temperatures exceeding 180°C. It is also too brittle for many modern processes. For this reason, researchers and companies began searching for synthetic rubber alternatives with superior performance characteristics.
Today, there are many different synthetic rubbers on the market. Synthetic rubber production has exploded in recent years, thanks to the demand for superior materials. In this post, we explore how it is made, the raw materials required, and how it compares to natural rubber.
Synthetic rubber is made of chemicals derived from crude oil or coal. Like plastics, it is made of polymer molecules; long chains that give it flexibility and strength. However, it is more elastomeric, letting it bend and stretch.
By contrast, natural rubber is made of renewable latex from the rubber tree. Because the chemical structure of latex is different, natural products have different physical properties.
There are several different types of synthetic rubber that companies and researchers have developed since World War II. Because of this, how they are made differs slightly. Therefore, in this section, we document the general synthetic rubber production process before diving into the specific properties of each type.
Manufacturers begin by refining the source material, usually oil or coal. This process lets them derive a substance with the correct molecular weight.
The next step is to create polymers (long molecules) that will give synthetic rubber its desirable properties.
To do this, manufacturers often use Naptha, a flammable liquid hydrocarbon mixture also used for plastics production. When manufacturers mix it with fossil fuel products and natural gas under the right conditions, it produces monomer units which then merge into polymer chains. Butyl rubber, styrene-butadiene rubber, and nitrile rubber are all made using this method.
The next step is to add compounds that encourage the polymer molecules to form polymer chains. These chains give synthetic rubber its superior qualities.
The vulcanisation process then transforms these polymer chains into a more durable material ready for industrial-scale application.
Lastly, manufacturers shape synthetic rubber into products, such as O-rings, gaskets, and so on. Technicians then assess their thermal stability and chemical properties before sending them to market.
Today, there are multiple natural and synthetic rubber products in production. In this section, we explore some of the artificially produced rubber products available.
Silicone rubber is used in applications that require good hygiene and resistance to high temperatures, such as food preparation. Manufacturers make it from a combination of silicone and oxygen, mixing in various additives to improve its properties. For example, some manufacturers add fluorine to silicone rubber to make it more resistant to chemicals. Others add vinyl for better vulcanisation or phenyl for higher flexibility at lower temperatures.
Butyl rubber production involves combining isoprene with isobutylene. Combining the two makes the rubber unsaturated and suitable for vulcanisation.
Ethylene propylene diene monomer rubber is a class M rubber made of saturated polyethylene chain elastomers. Mostly, people use it for garden hose tubing, pond liners, belts, electrical insulation, solar panel heat collectors, rubber bands, and speaker cone surrounds.
Nitrile-type rubber is made using an emulsion polymerization process from butadiene and acrylonitrile compounds. Acrylonitrile is a highly reactive substance. When mixed with butadiene, it forces a vulcanisation reaction, producing oil-resistant nitrile as a result.
Polybutadiene rubber or just butadiene rubber is a type of rubber made from solution polymerization of high molecular weight monomer 1,3-butadiene. Like the other rubber products in this list, polybutadiene rubber monomers come from petroleum processing. Manufacturers use this rubber-like substance directly in rubber products as well as plastics and some fuels.
Styrene butadiene rubber (SBR) is a combination of butadiene rubber and styrene, usually in a 3:1 ratio of the former to the latter. Adding styrene gives the rubber superior abrasion and crack resistance compared to standard formulations.
Methyl rubber is a rubber substance made by Germany in World War I via the polymerisation of dimethyl butadiene. It is rare today.
Lastly, neoprene is a type of rubber made of hydrochloric acid, acetylene and chloroprene. It is made by using chloroprene to bind molecules together into chips that are then melted with foaming agents and carbon pigments. Further heating causes the rubber to expand and take on its final form.
In summary, natural rubber comes from rubber trees. By contrast, synthetic rubbers come from crude oil and other hydrocarbons. Synthetic rubber tends to have superior properties compared to natural rubber in most consumer and industrial-scale applications. It is stronger, more flexible and resistant to high heat.
What synthetic rubber is made of depends on the type that manufacturers want to make. Most are made of petroleum byproduct-derived polymers.
Roughly 70 percent of the products the rubber industry makes are now synthetic. Production took off after the middle of the 20th century when manufacturers saw that they could use natural gases and cheap crude oil byproducts to create high-quality, durable materials.
Both rubbers and plastics are made from the same family of polymers. However, plastic is always synthetic whereas rubber is sometimes natural. The difference between plastic and rubber is the elasticity of their polymers. Plastic is far more rigid.
Synthetic rubber produced today can generate some toxic substances which may be dangerous to workers. However, end products are safe for consumers, including for food preparation.
Synthetic rubbers have superior properties to natural rubbers in general. For instance, they age better, are more resistant to weathering, and maintain their properties when exposed to oxidising compounds, high temperatures, and oils.
You can purchase synthetic rubber from WC Munsch & CO. We supply a range of different types of synthetic rubber. View more on our rubber materials page.
If you need any help or advice simply give us a call or fill in the enquiry form and one of our technical team will help you out.